237 research outputs found
Short-Range B-site Ordering in Inverse Spinel Ferrite NiFe2O4
The Raman spectra of single crystals of NiFe2O4 were studied in various
scattering configurations in close comparison with the corresponding spectra of
Ni0.7Zn0.3Fe2O4 and Fe3O4. The number of experimentally observed Raman modes
exceeds significantly that expected for a normal spinel structure and the
polarization properties of most of the Raman lines provide evidence for a
microscopic symmetry lower than that given by the Fd-3m space group. We argue
that the experimental results can be explained by considering the short range
1:1 ordering of Ni2+ and Fe3+ at the B-sites of inverse spinel structure, most
probably of tetragonal P4_122/P4_322 symmetry.Comment: 10 pages, 5 figures, 6 table
Controlling for transactions bias in regional house price indices
Transactions bias arises when properties that trade are not a random sample of the total housing stock. Price indices are susceptible because they are typically based on transactions data. Existing approaches to this problem rely on Heckman-type correction methods, where a probit regression is used to capture the differences between properties that sell and those that do not sell in a given period. However, this approach can only be applied where there is reliable data on the whole housing stock. In many countries—the UK included—no such data exist and there is little prospect of correcting for transactions bias in any of the regularly updated mainstream house price indices. Thispaper suggests a possible alternative approach, using information at postcode sector level and Fractional Probit Regression to correct for transactions bias in hedonic price indices based on one and a half million house sales from 1996 to 2004, distributed across 1200 postcode sectors in the South East of England
The Unusual Superconducting State at 49 K in Electron-Doped CaFe2As2 at Ambient
We report the detection of unusual superconductivity up to 49 K in single
crystalline CaFe2As2 via electron-doping by partial replacement of Ca by
rare-earth. The superconducting transition observed suggests the possible
existence of two phases: one starting at ~ 49 K, which has a low critical field
~ 4 Oe, and the other at ~ 21 K, with a much higher critical field > 5 T. Our
observations are in strong contrast to previous reports of doping or
pressurizing layered compounds AeFe2As2 (or Ae122), where Ae = Ca, Sr or Ba. In
Ae122, hole-doping has been previously observed to generate superconductivity
with a transition temperature (Tc) only up to 38 K and pressurization has been
reported to produce superconductivity with a Tc up to 30 K. The unusual 49 K
phase detected will be discussed.Comment: 11 pages, 8 figure
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Synchronisation and commonalities in metropolitan housing market cycles
This paper examines the degree of commonalities present in the cyclical behavior of the eight largest metropolitan housing markets in Australia. Using two techniques originally in the business cycle literature we consider the degree of synchronization present and secondly decompose the series’ into their permanent and cyclical components. Both empirical approaches reveal similar results. Sydney and Melbourne are closely related to each other and are relatively segmented from the smaller metropolitan areas. In contrast, there is substantial evidence of commonalities in the cyclical behavior of the remaining cities, especially those on the Eastern and Southern coasts of Australia
UK Housing Market: Time Series Processes with Independent and Identically Distributed Residuals
The paper examines whether a univariate data generating process can be identified which explains the data by having residuals that are independent and identically distributed, as verified by the BDS test. The stationary first differenced natural log quarterly house price index is regressed, initially with a constant variance and then with a conditional variance. The only regression function that produces independent and identically distributed standardised residuals is a mean process based on a pure random walk format with Exponential GARCH in mean for the conditional variance. There is an indication of an asymmetric volatility feedback effect but higher frequency data is required to confirm this. There could be scope for forecasting the index but this is tempered by the reduction in the power of the BDS test if there is a non-linear conditional variance process
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Spatial housing economics: a survey
This introduction to the Virtual Special Issue surveys the development of spatial housing economics from its roots in neo-classical theory, through more recent developments in social interactions modelling, and touching on the role of institutions, path dependence and economic history. The survey also points to some of the more promising future directions for the subject that are beginning to appear in the literature. The survey covers elements hedonic models, spatial econometrics, neighbourhood models, housing market areas, housing supply, models of segregation, migration, housing tenure, sub-national house price modelling including the so-called ripple effect, and agent-based models. Possible future directions are set in the context of a selection of recent papers that have appeared in Urban Studies. Nevertheless, there are still important gaps in the literature that merit further attention, arising at least partly from emerging policy problems. These include more research on housing and biodiversity, the relationship between housing and civil unrest, the effects of changing age distributions - notably housing for the elderly - and the impact of different international institutional structures. Methodologically, developments in Big Data provide an exciting framework for future work
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Affordability targets: Implications for Housing Supply
This report presents the results of an econometric modelling project, concerned with regional housing affordability, conducted for the ODPM between November 2004 and April 2005. The key outputs of the project are not just this report, but the model itself, the details of which are set out in the accompanying Technical Appendix, available via the ODPM website: www.odpm.gov.uk/housing. The team for the project was large, including fifteen individuals from nine organisations. The project was directed from the University of Reading. In addition to the team, the work was improved by help from an advisory group and a user group, consisting of members drawn from both central government and from the wider academic and policy communities
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